Highly Efficient Halide Perovskite Light‐Emitting Diodes via Molecular Passivation

Abstract

Metal halide perovskites are promising for applications in light-emitting diodes (LEDs), but still suffer from defects-mediated nonradiative losses,w hich represent am ajor efficiency-limiting factor in perovskite-based LEDs (Pe-LEDs). Reported here is as trategy to synthesize molecular passivators with different anchoring groups for defects passivation. The passivated perovskite thin films exhibit improved optoelectronic properties as well as reduced grain sizea nd surface roughness,thus enable highly efficient PeLEDs with an external quantum efficiency of 15.6 %u sing an imidazolium terminated passivator.F urther demonstrated is that the in situ formation of low-dimensional perovskite phase on the surface of three-dimensional perovskite nanograins is responsible for surface defects passivation, whichl eads to significantly enhanced device performance.O ur results provide new fundamental insights into the role of organic molecular passivators in boosting the performance of PeLEDs.

Phosphonate/Phosphine Oxide Dyad Additive for Efficient Perovskite Light‐Emitting Diodes

“…Figure 4d shows the normalized EL spectra at a voltage of 5 V. All the PeLEDs demonstrate similar green emission with a FWHM of 22 nm. Differing from other strategies to improve radiative recombination with a large spectra shift of > 10 nm, [11,26] the maximum EL peak shift is only 2 nm on introducing these additives.…”

“…[1][2][3][4][5][6] Introduction of additives is an important strategy to improve the device efficiency of PeLEDs, and they can be divided into ionic and neutral ones. [7][8][9][10][11] Among neutral additives, small molecules containing -NH 2 , CÀ OÀ C, C=O, P=O functional groups have been studied. [12][13][14][15][16][17][18][19] For example, amine-functionalized molecular additives were demonstrated to increase the defect passivation effect by reducing the hydrogen bonding between -NH 2 group and FA + (FA, formamidinium).…”

Improved phase purity and film quality in quasi-2D perovskite light-emitting diodes by an additive with the trimethacrylate group

“…This is a typical signal for the defect passivation of the perovskite lm. 28,29 Apart from the improved device EL performance, the device stability is also improved by TMPTA modication. As shown in Fig.…”

Effects of organic ligands on efficiency and stability of perovskite light-emitting diodes

“…ethylamine (EA), butylamine (BA), and phenylalkylamines, e.g. phenylethylamine (PEA), phenylbutylamine (PBA), were widely used as organic ligands to promote the perovskite films [38][39][40][41][42][43][44][45]. However, the interrelationships between efficiency/operation stability and the organic ligands additive have been rarely studied.…”